This invention relates generally to the arts of mining and conveying materials and more specifically to continuous mining machines and improvements therein for mining coal and the like.
It is well known to provide continuous mining machines with a single cutter head rotating on a horizontal axis having a length greater than the width of the mining machine. The cutter head moves vertically up and down the face of a mine to mine coal, normally beginning at the top of the face and moving progressively down to the bottom and then returning to the top of the face where the machine moves forward to sump the head into the face to begin another downward sweep. Generally speaking, the trade calls this type of machine a "fixed head" miner.
Heretofore, fixed head miners have generally used high pressure hydraulic systems for moving the extendible ends of the cutter head inward and outward. Such use of hydraulic fluids under relatively high pressures seems to cause leakage problems that are difficult and expensive to solve. In addition, fixed head miners generally have their cutter heads connected to a driving transmission including gears and shafts extending directly to the cutter head. This type of transmission is expensive, makes the cutter head more bulky, and requires it to be of a relatively large diameter. Thus it is difficult to use this type of transmission arrangement in a mining machine having a cutter head with a relatively small diameter.
It is known to provide gathering heads for conveyors, such as used in continuous mining machines, with counter-rotating tables or discs mounted on the deck or apron of the gathering head and to provide each rotating disc with upstanding radially extending vanes to sweep material onto a conveyor located between the counter-rotating discs. However, it has been found that arranging the vanes to extend radially reduces the ability of the vanes to efficiently sweep conveyed material onto the conveyor.